 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.internal.ide;

 import java.io.IOException ;
 import java.io.InputStream ;
 import java.net.URL ;
 import java.util.zip.CRC32 ;
 import java.util.zip.CheckedInputStream ;

 import org.eclipse.core.runtime.Assert;
 import org.eclipse.core.runtime.IBundleGroup;
 import org.eclipse.core.runtime.IBundleGroupProvider;
 import org.eclipse.core.runtime.IProduct;
 import org.eclipse.core.runtime.Path;
 import org.eclipse.core.runtime.Platform;
 import org.eclipse.jface.resource.ImageDescriptor;
 import org.eclipse.ui.internal.BundleGroupProperties;
 import org.eclipse.ui.internal.ProductProperties;

 /**
  * The information within this object is obtained from the about INI file.
  * This file resides within an install configurations directory and must be a
  * standard java property file.
  * <p>
  * This class is not intended to be instantiated or subclassed by clients.
  * </p>
  */
 public final class AboutInfo {
     private ProductProperties productProperties;

     private BundleGroupProperties bundleGroupProperties;

     private Long featureImageCRC;

     private boolean calculatedImageCRC = false;

     /**
      * The information contained in this info will apply to only the argument product.
      */
     public AboutInfo(IProduct product) {
         this.productProperties = new ProductProperties(product);
     }

     /**
      * This info object will apply to the argument bundle group.
      */
     public AboutInfo(IBundleGroup bundleGroup) {
         this.bundleGroupProperties = new BundleGroupProperties(bundleGroup);
     }

     /**
      * Returns the configuration information for the feature with the given id.
      *
      * @param featureId
      * the feature id
      * @param versionId
      * the version id (of the feature)
      * @return the configuration information for the feature
      */
     public static AboutInfo readFeatureInfo(String featureId, String versionId) {
         Assert.isNotNull(featureId);
         Assert.isNotNull(versionId);

         // first see if the id matches the product
 IProduct product = Platform.getProduct();
         if (product != null
                 && featureId.equals(ProductProperties.getProductId(product))) {
             return new AboutInfo(product);
         }

         // then check the bundle groups
 IBundleGroup bundleGroup = getBundleGroup(featureId, versionId);
         if (bundleGroup != null) {
             return new AboutInfo(bundleGroup);
         }

         return null;
     }

     private static IBundleGroup getBundleGroup(String id, String versionId) {
         if (id == null || versionId == null) {
             return null;
         }

         IBundleGroupProvider[] providers = Platform.getBundleGroupProviders();
         for (int p = 0; p < providers.length; ++p) {
             IBundleGroup[] groups = providers[p].getBundleGroups();
             for (int g = 0; g < groups.length; ++g) {
                 if (id.equals(groups[g].getIdentifier())
                         && versionId.equals(groups[g].getVersion())) {
                     return groups[g];
                 }
             }
         }

         return null;
     }

     /**
      * Returns the descriptor for an image which can be shown in an "about" dialog
      * for this product. Products designed to run "headless" typically would not
      * have such an image.
      *
      * @return the descriptor for an about image, or <code>null</code> if none
      */
     public ImageDescriptor getAboutImage() {
         return productProperties == null ? null : productProperties
                 .getAboutImage();
     }

     /**
      * Returns the descriptor for an image which can be shown in an "about features"
      * dialog. Products designed to run "headless" typically would not have such an image.
      *
      * @return the descriptor for a feature image, or <code>null</code> if none
      */
     public ImageDescriptor getFeatureImage() {
         return bundleGroupProperties == null ? null : bundleGroupProperties
                 .getFeatureImage();
     }

     /**
      * Returns the simple name of the feature image file.
      *
      * @return the simple name of the feature image file,
      * or <code>null</code> if none
      */
     public String getFeatureImageName() {
         if (bundleGroupProperties == null) {
             return null;
         }

         URL url = bundleGroupProperties.getFeatureImageUrl();
         return url == null ? null : new Path(url.getPath()).lastSegment();
     }

     /**
      * Returns the CRC of the feature image as supplied in the properties file.
      *
      * @return the CRC of the feature image, or <code>null</code> if none
      */
     public Long getFeatureImageCRC() {
         if (bundleGroupProperties == null) {
             return null;
         }

         if (!calculatedImageCRC) {
             featureImageCRC = calculateImageCRC(bundleGroupProperties
                     .getFeatureImageUrl());
             calculatedImageCRC = featureImageCRC != null;
         }

         return featureImageCRC;
     }

     /**
      * Calculate a CRC for the feature image
      */
     private static Long calculateImageCRC(URL url) {
         if (url == null) {
             return null;
         }

         InputStream in = null;
         try {
             CRC32 checksum = new CRC32 ();
             in = new CheckedInputStream (url.openStream(), checksum);

             // the contents don't matter, the read just needs a place to go
 byte[] sink = new byte[2048];
             while (true) {
                 if (in.read(sink) <= 0) {
                     break;
                 }
             }

             return new Long (checksum.getValue());
         } catch (IOException e) {
             return null;
         } finally {
             if (in != null) {
                 try {
                     in.close();
                 } catch (IOException e) {
                     // do nothing
 }
             }
         }
     }

     /**
      * Returns a label for the feature plugn, or <code>null</code>.
      */
     public String getFeatureLabel() {
         if (productProperties != null) {
             return productProperties.getProductName();
         }
         if (bundleGroupProperties != null) {
             return bundleGroupProperties.getFeatureLabel();
         }
         return null;
     }

     /**
      * Returns the id for this feature.
      *
      * @return the feature id
      */
     public String getFeatureId() {
         String id = null;
         if (productProperties != null) {
             id = productProperties.getProductId();
         } else if (bundleGroupProperties != null) {
             id = bundleGroupProperties.getFeatureId();
         }
         return id != null ? id : ""; //$NON-NLS-1$
 }

     /**
      * Returns the text to show in an "about" dialog for this product.
      * Products designed to run "headless" typically would not have such text.
      *
      * @return the about text, or <code>null</code> if none
      */
     public String getAboutText() {
         return productProperties == null ? null : productProperties
                 .getAboutText();
     }

     /**
      * Returns the application name or <code>null</code>.
      * Note this is never shown to the user.
      * It is used to initialize the SWT Display.
      * <p>
      * On Motif, for example, this can be used
      * to set the name used for resource lookup.
      * </p>
      *
      * @return the application name, or <code>null</code>
      *
      * @see org.eclipse.swt.widgets.Display#setAppName
      */
     public String getAppName() {
         return productProperties == null ? null : productProperties
                 .getAppName();
     }

     /**
      * Returns the product name or <code>null</code>.
      * This is shown in the window title and the About action.
      *
      * @return the product name, or <code>null</code>
      */
     public String getProductName() {
         return productProperties == null ? null : productProperties
                 .getProductName();
     }

     /**
      * Returns the provider name or <code>null</code>.
      *
      * @return the provider name, or <code>null</code>
      */
     public String getProviderName() {
         return bundleGroupProperties == null ? null : bundleGroupProperties
                 .getProviderName();
     }

     /**
      * Returns the feature version id.
      *
      * @return the version id of the feature
      */
     public String getVersionId() {
         return bundleGroupProperties == null ? "" : bundleGroupProperties.getFeatureVersion(); //$NON-NLS-1$
 }

     /**
      * Returns a <code>URL</code> for the welcome page.
      * Products designed to run "headless" typically would not have such an page.
      *
      * @return the welcome page, or <code>null</code> if none
      */
     public URL getWelcomePageURL() {
         if (productProperties != null) {
             return productProperties.getWelcomePageUrl();
         }
         if (bundleGroupProperties != null) {
             return bundleGroupProperties.getWelcomePageUrl();
         }
         return null;
     }

     /**
      * Returns the ID of a perspective in which to show the welcome page.
      * May be <code>null</code>.
      *
      * @return the welcome page perspective id, or <code>null</code> if none
      */
     public String getWelcomePerspectiveId() {
         return bundleGroupProperties == null ? null : bundleGroupProperties
                 .getWelcomePerspective();
     }

     /**
      * Returns a <code>String</code> for the tips and trick href.
      *
      * @return the tips and tricks href, or <code>null</code> if none
      */
     public String getTipsAndTricksHref() {
         return bundleGroupProperties == null ? null : bundleGroupProperties
                 .getTipsAndTricksHref();
     }

     /**
      * Return an array of image descriptors for the window images to use for
      * this product. The expectations is that the elements will be the same
      * image rendered at different sizes. Products designed to run "headless"
      * typically would not have such images.
      *
      * @return an array of the image descriptors for the window images, or
      * <code>null</code> if none
      * @since 3.0
      */
     public ImageDescriptor[] getWindowImages() {
         return productProperties == null ? null : productProperties
                 .getWindowImages();
     }
 }

